Use LiveData and ViewModel for ManageSecurityToken fragment

This hopefully also prevents some NPEs from google play crash reports.

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/livedata/GenericLiveData.java

@@ -3,6 +3,7 @@ package org.sufficientlysecure.keychain.livedata;
 
 import android.content.Context;
 import android.net.Uri;
+import android.os.SystemClock;
 
 import org.sufficientlysecure.keychain.daos.DatabaseNotifyManager;
 import org.sufficientlysecure.keychain.ui.keyview.loader.AsyncTaskLiveData;
@@ -10,6 +11,7 @@ import org.sufficientlysecure.keychain.ui.keyview.loader.AsyncTaskLiveData;
 
 public class GenericLiveData<T> extends AsyncTaskLiveData<T> {
     private GenericDataLoader<T> genericDataLoader;
+    private Long minLoadTime;
 
     public GenericLiveData(Context context, GenericDataLoader<T> genericDataLoader) {
         super(context, null);
@@ -26,12 +28,30 @@ public class GenericLiveData<T> extends AsyncTaskLiveData<T> {
         this.genericDataLoader = genericDataLoader;
     }
 
+    public void setMinLoadTime(Long minLoadTime) {
+        this.minLoadTime = minLoadTime;
+    }
+
     @Override
     protected T asyncLoadData() {
-        return genericDataLoader.loadData();
+        long startTime = SystemClock.elapsedRealtime();
+
+        T result = genericDataLoader.loadData();
+
+        try {
+            long elapsedTime = SystemClock.elapsedRealtime() - startTime;
+            if (minLoadTime != null && elapsedTime < minLoadTime) {
+                Thread.sleep(minLoadTime - elapsedTime);
+            }
+        } catch (InterruptedException e) {
+            // nvm
+        }
+
+        return result;
     }
 
     public interface GenericDataLoader<T> {
         T loadData();
     }
+
 }